Circuit-breaker.



H. S. BEAKES.

CIRCUIT BREAKER.

APPLICATION FILED OCT-23I 1913. 1,191,146. 1 Patented Jul ls, 1916.

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CIRCUIT BREAKER.

APPLICATION FILED OCT-23. I913.

Patented July 18, 1916.

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HOWARD S. BEAKES, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO THE UNIONSWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA.

CIRCUIT-BREAKER.

Application filed October 23, 1913.

To It whom it may concern.

Be it known that I, HOWARD S. BEAKES, a citizen of the United States,residing at NVilkinsbur-g, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inCircuit-Breakers, of which the following is a specification.

My invention relates to circuit breakers of the overload type, andparticularly to breakers of this type which are operated to open acircuit by a prolonged current above a given value but which are notoperated to open the circuit by a momentary surge of current above thegiven value or by a current of brief duration above the given value.

One object of my invenion is the provision of a circuit breaker of thistype in which the operation by momentary surges of current or by currentof brief duration above the given value is prevented solely by'electricor electromagnetic means, thus avoiding the necessity for mechanical orpneumatic means for accomplishing this purpose.

I will describe several forms of circuit breakers embodying myinvention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 is a view showing in sideelevation a circuit breaker of the magnet-and-armature type andincluding one form of means embodying my invention for preventingoperation by momentary surges. Fig. 2 is a view similar to Fig. 1 butshowing another form of means embodying my invention for preventingoperation by momentary surges or by current of brief duration above thegiven value. Fig. 3 is a view similar to Fig. 2 but showing amodification of the means shown therein for preventing opera tion bymomentary surges or by current of brief duration above the given value.Fig. 4: is a view showing a circuit breaker of the solenoid and plungertype including one form of means embodying my invention for preventingoperation by momentary surges.

Similar reference'characters refer to similar parts in each of theseveral views.

Referring first to Fig. 1, the reference character 1 designates aU-shaped yoke of magnetizable material, usually soft iron, to the insidefaces of the legs of which are secured two magnet cores 2 and 3 respec-Specification of Letters Patent.

Patented July 18, 1916.

Serial No. 796,834.

tively, also of magnetizable material usually soft iron. An armature aof magnet izable material, usually soft iron, is pivoted to the yokeabout midway between the two legs as shown, and is adapted to movebetween pole-pieces 2 and 5 on the ends of the two magnet coresQ and 3.This armature is prevented from actual contact with either pole-piece byshort core pins 5 and 6 of non-magnetizable material to prevent stickingdue to residual magnetism. Pole-piece 3 is preferably shaped somewhat asshown, so that when the armature lies against this pole-piece the airgap between the two will have low reluctance. The armature is biased bysuitable means, as here shown by gravity, to the position shown in thedrawing, that is, to engagement with core pin 5 of core 3.

Core 2 is provided with a winding 7 which forms part of a direct currentcircuit which the circuit breaker controls. The parts of the device areso proportioned that when the current in the circuit exceeds a certaingiven 'value, magnet 2 will be sufficiently powerful to raise armature 4unless this armature is held down by a force other than gravity. Onefeature of my invention is the provision of means controlled by currentin the circuit for exerting such another force on the armature during amomentary surge of current above the given value, but not during aprolonged current in excess of the given value, so that the armature 4Lwill not be raised by magnet 2 during a momentary surge of current abovethe given value. This means I will now describe.

Magnet core 3 is provided with a winding 10 which is included in a localcircuit which is in inductive relation to the main or line circuit, sothat variations in value of the current in the main circuit will causecurrents in the circuit of winding 10. As here shown, this'inductiverelation is secured by placing a second winding 11 on core 2 andconnecting it in circuit with winding 10, the circuit between windings11 and 10 being completed by conductors 12 and 13. Since the linecircuit which feeds winding 7 carries direct current, it is obvious thatwhen the value of the current therein is constant, no current will beinduced in winding 11 and winding 10 will therefore not beenergized, somagnet 3 then exerts no force on armature 1-. But when the value of thecurrent in the line circuit varies, current will be induced in winding11 during the period of such variation, and magnet 23 will then beenergized and will exert force on armature 1.

The operation of the parts of the device thus far described is asfollows: As long as the current in the line circuit is equal to or belowthe given value, magnet 2 is not strong enough to raise armature itagainst the force of gravity. Assume now that a momentary surge ofcurrent above the given value occurs in the circuit controlled by thebreaker; during the time the current is increasing in value, current inone direction is induced in winding 11, and while the line current is decreasing in value current in the other direction is induced in winding11, hence during the entire surge magnet 3 is energized and prevents thearmature 1 from being raised by magnet A comparatively small current inwinding is suiiicient to prevent armature 1- being raised by magnet 2even when the winding 7 of this magnet carries a comparatively heavycurrent, because of the relatively small air gap between the armatureand polepiece 3, and the relatively large air gap between the armatureand pole piece 2. Assume now that the current in the circuit controlledby the breaker rises above the given value and remains substantiallyconstant at a value above the given value. While the current is rising,induced current will flo as before in magnet winding 10 and the armature1 will be held down, but as soon as the line circuit current becomesconstant the induced current ceases so that magnet 3 no longer exerts aforce on the armature, and magnet 2 then raises the armature againstpole-piece 2.

The armature t may be employed to control one or more contacts in anydesired manner. As here shown, a stationary carbon block 1 1 is mountedin a support 16 of insulating material fixed to the upper leg of theyoke 1, and another carbon block is carried by a spring 17 which ismounted in a block 18 of insulating material fixed to the lower leg ofthe yoke 1. The spring 17 tends to straighten itself out so that contact1l15 is open, but the spring may be held by suitable means in suchposition that this contact is closed. As here shown, this meanscomprises a latch 19 pivotally conn cted with the spring at point 21 andhav ing a shoulder 19 adapted to engage a. hook 2O fixed to the block18. This latch 19 may be kicked out of hooking engagement with hook by atoe at fixed to the armature 4, so that when the armature is raised itcauses contact 1115 to be opened. The spring 17 may be replaced to theclosed position by a handle Contact 1 l15 is included in the circuitcontrolled by the circuit breaker;

in Fig. 1 I have indicated diagrammatically a circuit which may betraced as follows from battery 39 through a switch 38, a motor 37, wire9, winding 7, wire 8, contact 1 115, spring 17, wire to battery it isunderstood that this circuit is purely illustrative, and that a circuitbreaker embodying my invention is not limited to use in a circuit ofthis type.

The circuit breaker shown in Fi 2 is substantially the same as thatshown in Fig. 1, except as 10 the windings of magnets :2 and 3.Referring to Fig. 2, the winding for magnet 3, which I have heredesignated 10.

is formed of wire whose resistance increases with increase oftemperature; for example, it may be of iron wire, the resistance ofwhich at red heat is approximately three times its resistance when cold.This \Yilld. ing is energized from the line circuit in any suitablemanner, for example, as here shown by connecting it in shunt to thewinding 7 for magnet 2. The branch including winding 10" is from wire 8through wire 21, winding 10, wire 27 to wire 5). Winding 10 will thenalways carry current when current is flowing in the line circuit. Theparts of the apparatus are so proportioned that when the current in theline is below the given value at which it is desired that the circuitbreaker should operate, the current flowing in winding 10 is of suchvalue that the temperature of the wire in this winding is comparativelylow. The resistance of this winding is then comparatively low and thiswinding then takes a certain portion of the total current flowing in theline circuit, so that armature 1- is held down with considerable forceby magnet The portion of the current which then flows in winding 7 isinsuiiicient to cause magnet 2 to raise armature 1 against gravity andthe action of magnet 3. \Vhen, however, the current in the line circuitrises above the given value, and remains above this value for a definitelength of time. the temperature of the wire in winding 10 rises. Theresistance of winding 10 then increases so that winding 7 then carries alarger proportion of the total current than before, and the current inthis winding is then sullicient to cause magnet 2 to raise armature 1against gravity and against the action of magnet 3, thereby openingcontact 1-115. llut during a momentary surge of the line current abovethe given value there is not suilicient time for an appreciable rise oftemperature of winding 10, and the increased current in winding 7 is notsuilicient to raise armature hence the circuit breaker will not be opres Then, obviously, it will remain closed for a shorter length of timeon a current higher than this certain value, and for a longer length oftime on a lower current. The core pin which separates armature 4 frompolepiece 3, and which is designated by 5 in Fig. 2, is here shown asbeing comparatively long, for the reason that winding 10 is energizedwhen the circuit breaker should kick off, and if the air gap permittedby this core pin were too short the armature would be held down by eventhe small current then flowing in winding 10 It is understood that thecircuit breaker shown in Fig. 2 may be included in a circuit which issimilar to the circuit shown in Fig. 1.

Referring now to Fig. 3, the circuit breaker here shown is similar tothat shown in Fig. 2, except that the lower magnet 3 is omitted, and acoil of iron wire 10 is connected in shunt to winding 7 by wires 24 and25. In this modification the armature 4 is held down by gravity only.The parts are so proportioned that when the current in the line circuitis below the given value at which it is desired that the circuit breakershould operate, the current then flowing in coil 10 is of such valuethat the temperature of the wire in this coil is comparatively low. Theresistance of this coil is then comparatively low, and it takes acertain proportion of the total current flowing in the line circuit; thebalance of the current, which flows in winding 7, is then insuflicientto raise armature 4. When, however, the line circuit current rises abovethe given value and remains above this value for a certain length oftime, the temperature and consequently the resistance of the coil 1Orise, so that the winding 7 then carries a larger proportion of thetotal current than before, and this current is sufficient to raisearmature 4. But during a momentary surge of the line current above thegiven value, there is not suflicient time for an appreciable rise oftemperature of coil 10*, so that the current in winding 7 is notsuliicient to raise arma ture 4 and the circuit breaker is therefore notoperated. As explained hereinbefore in connection with Fig. 1, the partsmay be so designed that the circuit breaker will remain closed for adefinite length of time when subjected to a current of a certain valueabove the given value. This circuit breaker may be included in a circuitwhich is similar to that shown in Fig. 1.

Referring now to Fig. 4, I have here shown a circuit breaker of thesolenoid and plunger type embodying my invention. This circuit breaker,in the form here shown, comprises a rectangular frame 26 of magnetizablematerial, preferably soft iron, provided with a cross-piece 27 ofsimilar ma terial. The upper part of the frame 26 is provided with athreaded hole 26 into which is screwed a core 28 of magnetizablematerial, also preferably soft iron, which core is held in place by anut 28. The core 28 is provided with a central longitudinal hole 31through which freely passes a stem 30 of non-magnetizable material suchas brass, the lower end of which screws into a plunger 29 ofmagnetizable material, usually soft iron. This plunger passes freelythrough a hole 27* in the cross-piece 27, so it will be seen that theplunger 29 and stem 30 are free to reciprocate in a vertical path, beingguided by the hole in the core 28 and the hole in crosspiece 27. Thedownward movement of the plunger is limited by a stop comprising a pinof non-magnetizable material screwed into the bottom of the frame 26 andlocked by a nut 32 the upward movement is, of course, limited by theengagement of the plunger with the core 28. The core is provided withcorepins 33 of non-magnetizable material to prevent actual contact ofthe core with the plunger. 7 is a solenoid winding which surrounds thecore 28 and a portion of the plunger 29, and which forms part of adirect current circuit controlled by the circuit breaker. The parts ofthe device are so proportioned that when the current in the circuitexceeds a given value, solenoid 7 is sufiiciently energized to raise theplunger 29 unless the plunger is held down by some force other thangravity. As here shown, the means for holding the plunger down duringmomentary surges of current above the given value is substantially thesame as the means shown in Fig. 1; that is, I provide a winding 10 inthe form of a solenoid surrounding the plunger 29, which winding is inseries with a winding 11 which latter is in inductive relation to theoperating winding 7. The operation of the parts of the breaker thus fardescribed is substantially the same as the operation of the form shownin Fig. 1. That is, during a momentary surge of current in the circuitcontrolled by the breaker, current is induced in winding 11, and thecurrent which consequently flows in solenoid 10 exerts sufiicientinfluence on the plunger 29 to prevent the latter being raised bysolenoid 7. \Vhen. however, the current in the circuit controlled by thebreaker remains substantially constant at a value higher than the givenvalue, no current flows in solenoid 10, so that solenoid 7 is theneffective to raise plunger 29. The plunger 29 may be employed to controlone or more con tacts in any desired manner. As here shown, a spring 17is mounted in a block 33 of insulating material secured to the frame 26,and this spring is included in the circuit controlled by the breaker inthe same man ner as in the preceding Views. In Fig. 4 the spring isprovided with a hook 34 which coacts with a latch 35 pivoted in theblock The upper end of stem 30 carries a head 36 of insulating material,which, when the plunger is raised, strikes the latch 35 and so releasesthe spring 17. The circuits {or the solenoid winding 7 and for the retarding winding 10 are the same as those shown in Fig. 1 andhereinbefore explained. This circuit breaker may be included in acircuit which is similar to the circuit shown in Fig. 1.

Circuit breakers embodying my inven tion are adapted for the protectionof any circuit wherein it is desired that the circuit should be openedwhen the current is pro longed above a given value for an appreciablelength of time, but wherein a mo mentary surge of current above thegiven value will cause no harm so that it is undesirable that thecircuit should be opened by such a surge. They are, for example,particularly well adapted for the protection of motor circuits. Thecurrent drawn by a motor while starting is considerably in excess ofthat which is drawn after the motor is in operation, but this excess ofcurrent is only a momentary surge and does no harm to the motor or otherparts of the circuit; it, however, the motor is stalled or operates tooslowly and the circuit is not opened. the prolonged excessive currentwill injure the motor or other parts of the circuit. lVhen a circuitbreaker embodying my invention is used to protect a circuit of thischaracter it is adjusted to operate on a prolonged current slightly inexcess of ti it drawn by the motor when operating on full load. Then ifthe motor is stalled or operates too slowly, the circuit breaker will beoperated by the prolonged excessive current, but the circuit breakerwill not be operated by the momentary surge of current while the motoris being started.

Circuit breakers embodying my invention are also well adapted for use incircuits for the propulsion current for electric railways, in which casethe circuit breaker is usually adjusted to operate when the currentexceeds a safe maximum value. There are times when this maximum value isexceeded for a short period of time, such, for example, as when a largenumber of cars or trains are started at once. and it this period of timeis not too long the excessive current will do no harm. Circuit breakersembodying my invention can be adjusted to remain closed during a shortperiod of such excessive current, but to open it the excessive currentis prolonged tor a suiiicient length of time to be harmful.

Although I have herein shown and described only a few forms of circuitbreakers embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, an electric circuit; and a circuit breaker comprisinga winding e11- ergized from said circuit, a member adapted to be movedby said winding when the current in the circuit exceeds a given value, asecond winding adapted to prevent movement of said member by the firstwinding, means controlled by current in said circuit and responsive tomtm'ientary surges of said current above the given value for energizingsaid second winding, and a contact controlled by said member forcontrolling said circuit.

In combination, a circuit carrying direct current; and a circuit breakercom prising a winding included in said circuit, a member adapted to bemoved by said winding when the current in the circuit exceeds a givenvalue, a second winding adapted to prevent movement of said member bythe first winding, means for energizing said second winding inductivelyfrom said circuit whereby the second winding will be energized by amomentary surge of current above the given value in the circuit and willprevent movement ot the member by such.

surge, but whereby the second winding will not be energized by a.constant current in excess of said value and will therefore not preventmovement of the member by such constant current, and a contactcontrolled by said member for controlling said circuit.

3. A circuit breaker comprising a winding, a member adapted to beoperated by said winding when the current in the winding exceeds a givenvalue, a second winding tion to the first winding, and a contactcontrolled by said member.

l. A circuit breaker com 'irising an electromagnet having two windings,means for energizmg one o't said windlngs with di rect current, anarmature adapted to be on erated by said magnet when the current in thesaid energized winding exceeds a given value, a second electromagnetadapted to prevent operation of the aru'iature by the first-mentionedmagnet, the winding of the second magnet being connected with theremaining winding of the first magnet, and a contact controlled by saidarmature.

5. In combination, an. electric circuit, a movable member, meanscontrolled by current above a given value in said circuit for and acontact controlled by said member for opening said circuit.

6. In combination, an electric circuit, a movable member, meanscontrolled by current above a given value in said circuit for movingsaid member in one direction, means responsive to a momentary surge ofcurrent in said circuit above said given value but not responsive to acurrent of constant value regardless of such value for exerting a forceon said member in the opposite direction to prevent its movement, and acontact controlled by said member for opening said circuit.

7 In combination, an electric circuit; and a circuit breaker comprisinga Winding energized from said circuit, a member adapted to be moved bysaid Winding When the current in the circuit exceeds a given value, asecond Winding adapted to prevent movement of said member by the firstWinding,

means controlled by current in said circuit and responsive to momentarysurges of said current for energizing said second Winding, and a contactcontrolled by said member for controlling said circuit.

8. In combination, an electric circuit, a movable member, meanscontrolled by current above a given value in said circuit for movingsaid member in one direction, means responsive to a momentary surge ofcurrent in said circuit for exerting a force on said member in theopposite direction to prevent its movement, and a contact controlled bysaid member for opening said circuit.

In testimony whereof I afiix my signature in presence of two Witnesses.

HOWARD S. BEAKES.

Witnesses:

A.- HERMAN VVEGNER, R. L. KISTLER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. G.

